Investigation on the Reactions of Small Ring Ion Radicals and their Application to Synthetic Reactions

1.三种氘标记的烷基取代的双环[2.2.0]己烷的光敏化单电子氧化反应得到了主要保留构型的1，5-己二烯，这表明中间体环己烷-1，4-二基阳离子自由基在船形构象中发生环断裂，该构象与椅子和/或扭船构象通过相当大的能垒分开。环断裂的立体专一性依赖于电子受体的还原电位，表明自由基离子对中的环断裂和背电子转移在速率上是竞争性的.合成了4-噻二螺[2.1.2.2]壬-8-烯和几种螺环丙基芴，并考察了它们对缺电子化合物的反应性。前者分别与TCNQ和TCNE进行环加成反应，得到噻吩并菲衍生物.研究了1，4-桥连杜瓦瓶苯衍生物在光敏单电子氧化条件下的行为。它们经历中心σ键的断裂，得到弯曲的苯阳离子自由基，亲核试剂加入其中。在研究过程中，我们还成功地合成了一种具有高度弯曲性的苯衍生物--[4]对环蕃，一种新型的完全共轭双环体系--双环[4.2.2]十碳烯，以及一种邻位醌式环庚三酮衍生物--3，4-苯并环庚三酮。

1. The photosensitized one electron oxidation of three deuterium-labeled and alkyl substituted bicyclo[2.2.0]hexanes afforded 1,5-hexadienes predominantly with the retention of configuration, which indicated that intermediate cyclohexane-1,4-diyl cation radicals underwent ring cleavage in the boat conformation which was separated from the chair and/or twist-boat conformation by a sizable energy barrier. The dependence of the stereospecificity of ring fission on the reduction potential of electron acceptor implied that the ring cleavage and back electron transfer in the radical ion pairs were competitive in rate.2. 4-Thiadispiro[2.1.2.2]non-8-ene and several spiro-cyclopropylfluorenes were synthesized and their reactivities toward electron deficient compounds were examined. The former compound underwent cycloadditions with TCNQ and TCNE in which the use of ethereal solvent was critical and afforded thiophenophane derivatives.3. The behavior of some 1,4-bridged Dewar benzene derivatives under the conditions of photosensitized one electron oxidation was studied. They underwent the cleavage of central sigma bond to give bent benzene cation radicals to which nucleophiles added. In the process of study, we also succeeded in generating the most highly bent benzene derivative-[4]paracyclophane, a novel, fully conjugated bicyclic system-bicyclo[4.2.2]decapentaene, and an ortho quinoidal tropone derivative-3,4-benzotropone.